Showing papers on "Dielectric resonator antenna published in 1990"

Dielectric resonator antenna using aperture coupling

Abstract: A practical antenna configuration for use at microwave and millimetre wave frequencies is investigated. It consists of a circular cylindrical dielectric resonator fed by a microstrip feedline through a coupling aperture in the ground plane between them. Several elements, with different physical parameters, operating between 14 and 16GHz were constructed and tested. Experimental results confirm the effective and practical performance of the antenna structure.

RF Excited CO2 slab waveguide laser

Abstract: A CO 2 slab waveguide laser (10) disclosed including a pair of spaced apart electrodes (36,38) having exposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in the waveguide dimension but the mirror spacing from the end of the guide is based in part on the configuration of the unstable resonator. A unique support structure is disclosed for maintaining the electrodes in a spaced apart orientation without confining the discharge. Further refinements are disclosed for cooling the laser and for accommodating thermal expansion of the parts. Finally, an improved adjustable mirror assembly (26, 28) is provided which allows the tilt angle of the mirror to be varied from outside of the housing.

Laser system and method having a nonlinear crystal resonator

Abstract: A laser diode with a low reflectivity output facet provides infrared light to a nonlinear crystal resonator such that a portion of the infrared light is converted to blue light. A mirror is located on the opposite side of the nonlinear crystal resonator from the laser. The mirror allows the blue light to pass, but reflects the infrared light exiting the resonator back through the resonator and into the laser diode. The laser diode is thereby locked at the resonance frequency of the nonlinear crystal resonator.

Resonant mechanical sensor

Abstract: The sensor according to the present invention provides a device for measuring the magnitude of an applied load as a shift in resonant frequency of a mechanical resonator caused by load-induced strains on the resonator. The sensor includes a substrate, generally constructed of a semiconductor material, e.g. silicon, a diaphragm substantially supported along its outer periphery by the substrate, a boss abutting a region of the diaphragm remote from the outer periphery of the diaphragm, at least one resonator in the form of a beam having one end integral to the diaphragm proximate the region of the boss and the other end integral to the diaphragm remote from the boss, a hermetic seal for enclosing the resonator, and an exciter/detector for measuring changes in the natural frequency of the resonator due to an applied load. Preferably, the sensor includes a differential resonator configuration in which the resonators are positioned rectilinearly with respect to each other and are covered by the same hermetic seal.

Lower power oscillator with heated resonator (S), with dual mode or other temperature sensing, possibly with an insulative support structure disposed between the resonator (S) and a resonator enclosure

Abstract: A resonator heating element is attached to the surface of a crystal resonator. Resonator temperature sensing may be accomplished either by a sensor attached to the crystal enclosure, or through dual mode temperature sensing, or by both. A control system converts the sensed temperature into a series of variable-width pulses applied to the resonator heating element. Thus, the temperature sensing mechanism(s), control system and heating element comprise a temperature feedback control system which allows the crystal to stably operate at or very near its desired temperature. In an especially preferred embodiment, an integrated circuit from a switching power supply may be used in a novel manner to perform certain of the functions in the temperature feedback control loop. Plural resonators may be present in the enclosure, one of which may be directly involved in temperature sensing. In other embodiments, a ring-shaped insulative structure may additionally be disposed between the resonator and its enclosure.

Resonant frequency of cylindrical dielectric resonator placed in an MIC environment

Abstract: An effective dielectric constant technique to determine the resonant frequency of the TE/sub 01 delta / mode of a cylindrical dielectric resonator placed in a microwave integrated circuit (MIC) environment is discussed. An expression for the dielectric constant epsilon /sub eff/ which makes it possible to obtain results that compare favorably with rigorous methods is given. Experimental results demonstrating the method's validity are also reported. For a given resonant frequency, closed-form expressions for computing the height of the resonator are given. >

Voltage controlled oscillator including a saw resonator

Abstract: A voltage controlled oscillator includes a resonant circuit formed of an impedance in series with a voltage variable capacitance. The impedance consists of a surface acoustic wave resonator in parallel with either an inductance coil or another acoustic wave resonator.

Surface acoustic wave waveguide-coupled resonator notch filter

Abstract: A surface acoustic wave (SAW) waveguide-coupled resonator filter is overcoupled to produce an essentially constant conductance and susceptance over at least the bandwidth of a desired notch filter. The SAW resonator filter is embedded in a bridged-T allpass circuit to provide the pair of equal capacitances of the circuit, and the resonator ground is connected to one terminal of the parallel inductor of the circuit having the other terminal connected to a system ground.

A sensitive optically excited resonator pressure sensor

Abstract: A novel pressure-sensitive micromechanical resonator sensor has been fabricated by anisotropic etching of silicon. The resonator is driven into transverse vibration when a laser beam, intensity modulated at the natural frequency of the resonator, is incident at its centre. A separate heterodyne interferometer is used to probe the vibration. Pressure applied to the sensor causes a change in its natural frequency and we report that the pressure sensitivity of the resonance frequency changes from 3.5%/bar to 31%/bar for different sensor parameters.

Method for ascertaining mode hopping free tuning of resonance frequency and the Q-value of an optical resonator and a device for carrying out the method

Abstract: Method and apparatus to ensure tuning without mode hopping of the resonator frequency and tuning of the Q-value of an optical resonator of the type comprising a partially reflecting resonator mirror (2) and a movable reflecting optical grating, with grooves (GR) parallel to the resonator mirror, intended to function as a wavelength selective reflector and which may comprise optical elements between the mirror and the grating, said optical elements being intended for collimation, amplification (4) and filtering of the radiation in the resonator, so that when changing the resonance wavelength (μ) of the resonator or its Q-value, the grating is moved in such a way that a line (C) on the grating which is defined at a tuned initial position of the resonator by the intersection of the plane of grating grooves (M) and the virtual mirror plane (5) of the resonator mirror, remains at a distance less than μ/4 from the virtual mirror plane, which as a result of chromatic dispersion in the resonator media slides in distance to the fixed mirror with said resonator wavelength during the movement

Strip-line for propagating microwave energy

Abstract: A device for propagating microwave energy to a plasma discharge tube from an antenna coupled to a microwave generator includes a hollow rectangular conduit and a strip-line resonator or strip-line conductor disposed therein. The discharge tube is mounted perpendicular to and through a central opening in the strip-line resonator and is disposed at a distance, from one end of the strip-line where the antenna is located, of one-half the wavelength of the microwave energy and one-quarter wavelength from the opposite end. The strip-line is attached to one end of the rectangular conduit and is supported by a dielectric member at a point one-quarter wavelength from the antenna. Microwave energy is propagated from the antenna by the strip-line dimensioned to the resonant frequency of the microwave the energy. A gas, such as argon or helium, is introduced into the discharge tube and is ionized by microwave energy to form a plasma.

Use of a Fabry-Perot Resonator for the measurement of the surface resistance of high T c superconductors at millimeter wave frequencies

Abstract: The use of a Fabry-Perot Resonator to measure the surface resistance of bulk and thin film samples of YBa2Cu3O7-δ at W-band frequencies is described. The Fabry-Perot measurement technique provides a more convenient size, higher Q and is capable of determining the surface resistance more accurately than cylindrical resonators at these frequencies.

Simple model for optical extraction from a flowing oxygen-iodine medium using a Fabry-Perot resonator

Abstract: A loaded-gain model of a CW flowing oxygen-iodine medium is described, and its principal assumptions and approximations are discussed. The model includes pumping of the upper laser level by O(2)(1 Delta), deactivation losses by water, and stimulated emission. The solution of the model in the absence of flux is obtained, from which a small-signal gain is determined. The model is solved for the output power from a Fabry-Perot resonator as a function of the medium and resonator parameters. It is shown that the maximum available power from the medium is determined by the O(2)(1 Delta) concentration at the nozzle exit plane.

Two-dimensional periodic structures in a nonlinear resonator

Abstract: The formation of a periodic transverse structure in the light field in a resonator consisting of mirrors and a thin layer of a nonlinear medium is considered. It is shown that, when the resonator length is a multiple of one half of the Talbot length, there exist periodic structures that are self-imaged under propagation through both the empty part of the resonator and the nonlinear medium. The influence of aperture losses is estimated. It is suggested that this type of a resonator may be useful for diode-array-pumped solid-state lasers.

Dielectric microwave resonator probe

Abstract: A dielectric resonator probe for measuring surface resistance of a test material, particularly at cryogenic temperature, is provided. A dielectric resonator is mounted near to but spaced from a conductive plate and is positioned in contact with a test material. Preferably, a low-loss dielectric spacer separates the resonator from the upper plate. The dielectric resonator has a larger lower surface area than upper surface area. The dielectric resonator includes a hole therethrough for increasing mode separation and for accommodating a mounting bolt. The mounting bolt is preferably nonconductive and is coupled to a spring for resiliently mounting the resonator and spacer to the plate so as to accommodate differential thermal expansion of the components.

Microstrip line type resonator

Abstract: A compact and high-Q microstrip line type resonator (30) which comprises a rectangular parallelepiped dielectric plate (42) having a first ground conductor (38) on the bottom surface, a second ground conductor on the four of all side surfaces (32a,32b,34,40) of the dielectric plate (42) connected to the first ground conductor (38), and a microstrip line conductor (36) provided on the top surface of the dielectric plate (42). The length of the strip line conductor (36) can be selected from 1/2 or 1/4 wavelength of the frequency of the signal which is applied to the resonator (30). Further, the microstrip line type resonator (30) can be covered by another dielectric plate to form a tri-plate type resonator.

Superconductor Josephson junction strip resonator sensor for measuring magnetic flux

Abstract: A sensor for measuring magnetic flux has at least one hole or opening in a strip resonator of superconductive material defining a ring in which a Josephson element is integrated into the strip resonator and coupled thereto so that attenuation in the tank circuit formed by the ring when a standing wave is established in the strip resonator can be picked up capacitively by a further strip conductor.

Method of measuring dielectric material constants and measuring device employed therefor

Abstract: A method of measuring dielectric material constants, which includes steps of forming a dielectric resonator by providing a plurality of coupling terminals for input and output of signals, on a shield case, with a dielectric sample being disposed within the shield case, constituting an oscillation circuit together with the dielectric resonator by connecting a positive feed-back circuit including an amplification circuit, between the signal output coupling means and the signal output coupling means, and measuring variation in an oscillation frequency of the oscillation circuit by heating the dielectric sample through injection of a high frequency power into the particular coupling terminal, so as to obtain a specific material constant of the dielectric sample based on the variation of the oscillation frequency, and, also a measuring device employed for effecting the measuring method.

A dielectric resonator support system for a waveguide

Abstract: A system for supporting a dielectric resonator (12) in a circular waveguide (10). A dielectric resonator is held in its optimum position using support posts or rods (11). The support rods are made from a suitable dielectric material, and slip fitted in holes (14) provided at 90° intervals around the periphery of the dielectric resonator. The support rods are affixed to the waveguide, by gluing or being screwed in place. The support rods are slip fitted such that they are allowed to expand, due to temperature, without causing stress on the dielectric resonator, thus the dielectric resonator is held in position without being affixed to its supporting structure. This is an inexpensive and simple solution to a complex problem. The support system is self-centering and free from all stress. The support system utilizes a minimum amount of supporting material which permits realization of the best unloaded Q.

Radio frequency antenna for a nuclear magnetic resonance tomography apparatus

Abstract: A radio frequency antenna for a nuclear magnetic resonance tomography apparatus has interior conductors which form a transmission line resonator with at least one shortening capacitor. The transmission line resonator can resonate at a plurality of resonator frequencies, and a trap circuit is provided for decoupling the interior conductors from the other conductors. The antenna can be operated at a number of different resonate frequencies, for example, at frequency f1 =170 MHz for protons (hydrogen) and F2 =69 MHz for phosphorous.

Frequency splitting in microstrip rhombic resonators

Abstract: The introduction of a step discontinuity in one of the arms of a symmetrically coupled microstrip rhombic resonator creates a disturbance in the symmetry of the resonator, and results in the splitting of the resonant frequency. This is evidence of the fact that two degenerate modes are excited in the resonator and experiments carried out verify this phenomenon. Design curves are also presented to show the dependence of resonator performance on its parameters, as well as substrate parameters. This resonator could find applications in double tuned narrowband microwave filters. >

Crystal resonator with acceleration sensitivity adjustable by external circuit means

Abstract: A crystal resonator device having a plurality of coupled resonators in which the relative phase and magnitude of the resonator excitation currents is controlled by electrical circuit means such as reactance components connected in series with one or more of the resonators to thereby minimize or otherwise control the acceleration sensitivity of the device.

Dielectric resonator circuit

Abstract: A resonator element formed of a half or a quarter of dielectric cylinder contacts an electrically conductive plane via the resonator element's radially cut side which includes the axis of the cylinder, accordingly, resonates in TE 01 δ -mode. On an opposite side of the electrically conductive plane there is provided an unbalanced transmission line, for example, of a strip line type or a coaxial line type. An end of the transmission line is electromagnetically coupled via a dielectric material in the transmission line or directly with the radially cut side of the resonator element through an opening provided on the electrically conductive plane. Coupling circuit according to the present invention allows a compact overall circuit configuration.

Resonator for a magnetic resonance imaging apparatus

Abstract: A resonator for use in a magnetic resonance imaging apparatus for transmitting and receiving high frequency signals is formed by a combination of two antenna sub-systems, which generate respective magnetic fields which are perpendicular to each other, with the currents in the sub-system being phase-shifted by 90° relative to each other, and each sub-system includes a capacitance which defines the resonant frequency. Each of the sub-systems forms a current loop, the current loops containing a common current network and a common base plate, which serves as a return path for both current loops. The junctions of the current network are connected via the resonant capacitances to the base plate, which consists of electrically conductive material. A circularly polarizing resonator is achieved for the transversal, fundamental field of the imaging apparatus, with the resonator also being capable of use as a surface resonator if the spacing between the current network and the base plate is small.

Compact stripline filter with fixed capacity between coupled resonator fingers

Abstract: An improved stripline filter is disclosed which includes a laminate of a pair of dielectric substrates each having an outer surface provided with a ground conductor, and conducting resonator means provided between each of the two adjacent dielectric substrates and having a plurality of parallel resonator fingers each having an open circuit end and a base end electrically connected to said ground conductor, in which the ground conductor has extended portions corresponding in number to the number of the resonator fingers, each of the extended portions extending toward the open circuit end of the corresponding resonator finger and terminating with a predetermined space from the open circuit end of the corresponding resonator finger.

Passive absorptive resonator laser system and method

Abstract: Pump laser light is focused into a solid state laser material. A resonator is positioned around the laser material. The resonator is comprised of reflectors which have high reflectivity at both the pump light frequency and the solid state laser light frequency. The resonator is impedance matched to the pump laser. The pump light resonates inside the solid state laser material until practically all of it is absorbed.

Microwave-excited high-power laser

Abstract: To provide more economical excitation of a high-power laser comprising a resonator having mirrors arranged in spaced, opposite relation to each other in the direction of a resonator axis and a beam path extending in both the direction of the resonator axis and a transverse direction perpendicular thereto, a gas-discharge volume permeated by the beam path and containing laser gas, and two facing wall surfaces extending substantially parallel to the resonator axis and to the transverse direction and enclosing between them and thereby delimiting the gas-discharge volume, it is propsoed that at least one wall surface be formed by a dielectric wall, that a microwave resonance structure separate from the laser gas in the gas-discharge volume be placed on the dielectric wall and have an opening facing the dielectric wall and bring about in an area of volume of the gas-discharge volume opposite the opening a microwave excitation of the laser gas, and that microwaves be introducible into the microwave resonance structure from a microwave source.

Surface resonator for nuclear spin tomograph - consists of two partial systems with perpendicular magnetic fields, and currents 90 deg. out of phase

Abstract: The surface resonator consists of two partial systems. The partial system magnetic fields (B11,. B12) are mutually perpendicular and their currents (I11, I12) are 90 deg. out of phase. Each partial system has at least one resonance capacitance and two current loops enclosing the associated magnetic field in the resonator plane perpendicular to the base field. The useful part of the field in the object region lies outside the resonator plane. USE/ADVANTAGE - Diagnostic arrangement produces stimulation pulses with HF field vector components only perpendicular to base field.

Fiber optic resonator interferometer gyroscope having a resonator loop formed of two coupled lengths of optical fiber

Abstract: A fiber resonator gyro in which the resonator loop includes a first length of fiber having opposed ends into which respective clockwise and counterclockwise beams are launched. A second length of fiber is connected by two coupler means to spaced portions of said first length to form the loop. The couplers are preferably four-way couplers which have ports for dumping resonant radiation.